For the first time since the civil war, which left 75,000 dead or missing in El Salvador between 1980 and 1992, a former member of the military has been asked to restore law and order. Last month Mauricio Funes, the country’s first leftwing president since the end of the conflict, swore in retired general David Munguia Payes, previously the defence minister, as the new minister of justice and public security.

The Farabundo Martí National Liberation Front (FMLN), the former Marxist guerrilla organisation and now the ruling party, condemned the decision. Human rights campaigners and magistrates joined in the protest, maintaining that his appointment was a violation of the almost 20-year-old peace agreement, which banned the military from law enforcement and set up a national civilian police force.

With 16 murders a day, El Salvador is vying with Honduras for the dubious distinction of the highest rate of homicides in the world. On the route from Colombia to Mexico, Central America is the prey of drug traffickers, and to make matters worse mara youth gangs have terrorised the country for the past decade.

Funes has already tasked the army with supervising prisons and sensitive areas. The previous justice minister was a former FMLN commander, Manuel Melgar, who was out of favour with Washington because he took part in a guerrilla attack in 1985 in which four US marines lost their lives. FMLN sources attributed his resignation last month to US pressure.

“El Salvador may see a spiral of violence comparable to Mexico,” said the FMLN member of parliament Roberto Lorenzana. “When the Mexicans militarised law and order enforcement, the cure proved even worse than the disease.”

The FMLN has no personal objection to Munguia, who commanded an artillery brigade during the civil war, nor have any charges of human rights violations been brought against him. On the contrary, he has supported the ruling party for several years and was promoted to the rank of general thanks to the leftwing government. But his appointment seems to be the last straw in a growing rift between president and party.

Former guerrillas, now senior police officers, are threatening to resign in protest at the decision to make them take orders from an army general, even if he has retired.

“I ask to be judged on the basis of results after a year on the job,” Munguia said as he was sworn in. The next day Funes and his new minister met police leaders in an attempt to end the unrest.

Rightwing and leftwing governments in the region are making increasing use of the armed forces in their battle against crime.